1. Field of the Invention
The present invention relates to a driving apparatus of a plasma display panel (PDP), and more particularly, the present invention relates to a circuit for driving a scan electrode of the PDP.
2. Discussion of the Background
Generally, a PDP uses plasma generated by gas discharge to display characters or images, and it may include more than several tens of thousands to millions of pixels arranged in a matrix. A PDP may be classified as a direct current (DC) type or an alternating current (AC) type according to driving voltage waveforms and discharge cell structures.
When driving the AC PDP, a unit frame may be divided into a plurality of subfields for time division gray scale display, and each subfield may include a reset period, an address period, and a sustain period.
In the reset period, wall charges formed by a previous sustain-discharge may be erased, and each cell is initialized to stably perform a subsequent addressing operation. In the address period, each cell is selected to be turned on or turned off, and wall charges accumulate in the cells that are selected to be turned on (i.e., addressed cells). In the sustain period, a sustain discharge waveform may be alternately applied to a scan electrode and a sustain electrode to cause a discharge that displays an image on the addressed cell.
Conventionally, a ramp waveform may be applied to a scan electrode to establish wall charges in the reset period, as shown in FIG. 1 and disclosed in U.S. Pat. No. 5,745,086. In other words, a gradually rising ramp waveform may be applied to the scan electrode, followed by a gradually falling ramp waveform. In this case, since an ability to precisely control the wall charges may significantly depend on the gradient of the ramp, the wall charges may not be precisely controlled within a predetermined time frame.
Further, although a final voltage Vnf of the ramp falling waveform and a voltage Vscl applied to a selected scan electrode during the address period may be the same, separate transistors may be used for respectively transmitting the voltages Vnf and Vscl. In other words, a driver may have to be coupled to a contact of the scan electrode and to the transistor, which may be incapable of applying the pulse type voltage Vnf. Thus, separate transistors may be necessary: one for transmitting the voltage Vnf, and the other for the transmitting the voltage Vscl.